Changes

My example still holds, I think. The entropy of the water decreases and the water is an open system.

My example still holds, I think. The entropy of the water decreases and the water is an open system.

Also, the equation for the change in entropy above is a precise mathematical equation that '''defines''' the change of entropy. [[User:Richardm|Richardm]] ([[User talk:Richardm|talk]]) 14:24, 19 September 2016 (EDT)

Also, the equation for the change in entropy above is a precise mathematical equation that '''defines''' the change of entropy. There is no other contribution from the coffee/water.

 

In fact, we could replace this with a lump of some material (a sphere with a radius of 10 cm for example) in space. We heat the material up and surround it in a perfectly insulating sphere of material to shield it from us, let's say this sphere is 1 light-year in radius (so that in the time frame of our experiment, the lump of material and insulation cannot interact). If we watch the sphere for 10 minutes, it cools down via radiation and so its entropy decreases. [[User:Richardm|Richardm]] ([[User talk:Richardm|talk]]) 14:24, 19 September 2016 (EDT)